1. Field of the Invention
The present invention relates to a regulator for a gas fuel engine and particularly, to a regulator for a gas fuel engine capable of preventing deterioration in the quality of components caused by excessive heat-input that is supplied from a frozen preventing means.
2. Description of the Related Art
The use of compressed natural gas (CNG) as a fuel for automobiles has been focused in view of the energy saving and the environmental anti-pollution. In general, the compressed natural as stored at high pressure in a gas container mounted in the rear part of a vehicle and supplied to the engine. Prior to supplied to the engine, the compressed natural gas shall be decompressed and mixed with a proper amount of air. For decompression of the natural gas, in general, a regulator is provided in a midway of a gas supply conduit between the gas container and the engine.
It is however known that the decompression in the regulator causes adiabatic expansion thus resulting in sharp cooling down to freeze the regulator. For preventing such freezing of the regulator, a variety of measures have been developed. For example, Japanese Patent Laid-open Publication No. (Hei) 7-89813 discloses a system in which a cooling water conduit for feeding hot water from the water jacket of the engine to the heat exchanger in a cabin of a vehicle has a branch which extends across a water passage in the regulator to warm up the regulator with the hot water. The regulator is thus prevented from freezing by a flow of the hot water in the water passage and will hence be ensured in smooth action of pressure control.
Any conventional regulator has the following problems. As the atmospheric temperature rises or the load to the engine soars, the cooling water may be increased in the temperature and thus the temperature of its portion in the water passage of the regulator rises up excessively. Such an excessive rise in the temperature of the cooling water in the water passage, over a degree appropriate for prevention of freezing may especially deteriorate the elasticity of rubber materials of particular components those made of rubber materials in the regulator during a long service period. When the elasticity of the materials is declined, the effective clamping force will decrease or the accuracy of the pressure control will be degraded.